Ground effect machine employing recirculation and controlled distribution of lift



Aug. 9, 1966 R coss ETAL 3,265,141

GROUND EFFECT NIACiIINE EMPLOYING RECIRCULATION AND CONTROLLED DISTRIBUTION OF LIFT 3 Sheets-Sheet 1 Filed Oct. 18, 1961 KEITH R.COSSAIRT INVENTOR. HUGH B.MONTAGUE Aug. 9, 1966 K. R. COSSAIRT ET AL GROUND EFFECT MACHINE EMPLOYING REGIRCULATION AND CONTROLLED DISTRIBUTION OF LIFT 3 Sheets-Sheet 2 Filed Oct. 18, 1961 KEITH R. COSSAIRT JNVENTOR. HUGH B. MONTAGUE Aug. 9, 1966 K. R. COSSAIRT ET AL 3,265,141

GROUND EFFECT MACHINE EMPLOYING RECIRGULATION AND CONTROLLED DISTRIBUTION OF LIFT 3 Sheets-Sheet 5 Filed Oct. 18, 1961 KEITH R.COSSAIRT INVENTOR.

HUGH B. MONTAGUE United States Patent GRQUND EFFECT MACHINE EMPLOYING RE- CIRCIJLATION AND CONTROLLED DISTRIBU- TION 0F LIFT Keith R. Cossairt, Orlando, Fla, and Hugh B. Montague,

Denver, Colo., assignors to Martin-Marietta Corporation, Middle River, Md, a corporation of Maryland Filed Oct. 18, 1961, Ser. No. 145,920

6 Claims. (Cl. 180-7) This invention relates to a ground effect machine and more particularly to such a machine employing an ejector recirculating principle for obtaining primary lift for the vehicle by virtue of the centrifugal reaction of a curved jet of fluid which serves to create a pressure under the base of the vehicle, and additionally to create a. vertical reaction as a result of the change of momentum of the flow in the recirculating duct work.

In the past, various ground effect machines have been proposed, but in each known instance such machines have suffered from rather pronounced disadvantages such as dust and spray, large internal losses, low efficiencies, limited forward speeds and other such problems that have thus far served to prevent these machines from attaining wide popularity.

The prior art has also taught the use of certain recirculation techniques heretofore employed, but these arrangements have suffered from deficiencies such as short lived compressor blades, excessive duct Work and even smaller efficiencies than more conventional ground effect machines.

Our invention proposes a ground effect machine utilizing recirculation techniques for creating and sustaining a pressure on the underside of the machine, employing a plurality of recirculating ejector units disposed on at least a portion of the periphery of the machine. Each of these units comprises adjacent inlet and outlet slot-s located along the underside of the periphery of the machine and curved duct members interconnecting these slots for conducting a flow of air therebetween. Means such as a series of nozzles are disposed adjacent the inlet slots for directing quantities of high velocity primary air into the inlets, with such primary air as well as educted secondary air thereby being caused to flow through the curved duct members and thence emanate from the outlets downwardly as well as inwardly toward the underside of the machine. The inlet slots are arranged to receive most of the air emanating from the outlet slots after it has undergone a change of angular momentum in the ducts, such air representing the aforementioned secondary air educted into the inlets, thus creating a recirculating flow of air at the periphery of the machine. This recirculating flow principally serves to create and sustain a pressure on the underside of the machine for the support of same, although additionally the change of momentum of the recirculating air flow contributes an additional portion of lift, the exact proportion varying with the height of the machine above the ground.

Advantageously, our recirculating ejector unit design has no moving parts to be damaged or quickly eroded by dust or other particles often entrained in the recirculating air. Moreover, the recirculating feature reduces substantially dust and spray and 'also reduces the momentum drag of the vehicle by a factor equal the mass augmentation, which typically is a factor of 25 to 40.

These and other objects, features and advantages of this invention will be more apparent from a study of the enclosed drawings in which:

FIGURE 1 is a perspective View of a small ground effect machine of an exemplary type, which according to this invention uses peripherally disposed recirculating "ice ejector units for providing and maintaining a base pressure under the vehicle to serve as the primary lift for the machine;

FIGURE 2 is a fragmentary view illustrating a tail configuration that can be used upon our ground effect machine instead of the tail shown in FIGURE 1;

FIGURE 3 is a side elevational view of \an exemplary machine with a number of portions cut away to reveal internal construction;

FIGURE 4 is an enlarged showing of a typical recirculating ejector unit according to this invention;

FIGURE 5 is a fragmentary perspective view, revealing a length of recirculating ejector unit such as is commonly employed along a portion of the perimeter of the machine, with portions of the unit removed to reveal the arrangement of primary air nozzles therein;

FIGURE 6 is a perspective view taken from below a machine according to this invention, revealing the manner in which high velocity air is injected along the underside of the device;

FIGURE 7 is a fragmentary view of a portion of an ejector unit revealing the use of control vanes therein; and

FIGURE 8 is a fragmentary portion of the ducting used in the central portion of the machine to eject air used for stabilizing the craft.

Referring to FIGURE 1, the ground effect machine 11) is shown equipped with pilots compartment 11 and peripheral recirculating ejector units 12 disposed in this instance substantially completely about the perimeter of the machine. Air inlets 13 are provided for supplying air to engine 14, which appears in FIGURE 3, and it is the engine or engines which generate the substantial quantities of air required for providing both support and forward thrust for this vehicle. The primary lift of the vehicle is of course supplied by the recirculating ejector units, the lift being directly obtained as a result of jet reaction and indirectly as a result of increasing the base pressure. The relationship of direct and indirect lift is a function of the operating height of our machine, with the preponderately greater proportion of total lift being derived from the base pressure component at lower operating heights, and the significance of the lift due to jet reaction increasing with height above the ground. Thrust unit 15, which appears in FIGURES 1, 2 and 3, is employed for producing sufficient forwlard thrust for the vehicle to travel over land or over water at considerable speed.

The engine of our ground effect machine may be an ordinary piston engine driving an air compressor for supplying quantities of compressed air for the sustaining of the machine and the forward thrust thereof, but we prefer to use one or more gas turbine engines.

As depicted in FIGURE 3, the gas turbine 14 obtains its air supply from the nearest intake duct 13 and delivers quantities of air at elevated pressure to header or plenum 16. From this principal header one or more forwardly disposed ducts 17 deliver compressed air to a secondary header 18 and thence to the plurality of high pressure nozzles 15 disposed in the fiorwardmost recirculating ejector unit 20 of the machine, whereas rearwardly extending duct 21 carries similar quantities of high pressure air to a rear secondary header 22 and thence to high pressure nozzles 23 disposed in recirculating eljgctor unit 24 located along the rear portion of machine Duct 25 obtains air from manifold 16 and delivers it to a secondary header 26 and thence to a plurality of nozzles 27 that are arrayed as shown in FIGURE 1 along the inlet end 28 of thrust unit 15. The high pressure air injected into the inlet 28 of the thrust unit brings about an eduction of substantial quantities of secondary air from the atmosphere, which flows into thrust unit 15, the amount of air flowing through this unit being of substantial enough quantity as to produce a sizeable amount of thrust.

The unit 15 may utilize a porous sidewall member 31 'of circular or rectangular configuration disposed in its mixing chamber, to which air or exhaust gases may be delivered for bounadry layer control reasons. As shown in FIGURE 3, duct 32 may be disposed between the exhaust portion of engine 14 and porous sidewall member so as to carry the exhaust gases to the mixing chamber of the thrust unit 15. Not only is the thrust of the ejector increased by reducting the internal frictional forces along the side walls of the ejector and by increasing the secondary mass flow, but, as a result of the low static pressures in this region, the gas turbine is effectively supercharged.

The ejectior device for obtaining forward thrust, shown in FIGURES 1, 2 and 3, is one of several systems that can be used. The principal advantages of an ejector thrust unit are its simplicity, light weight, and the capability given the system for proportioning the total installed power, by a valving arrangement hereinafter described to proportion the airflow in order to achieve the lifting effort and forward velocity desired. Other more conventional thrust units could comprise propellers, jet engines, rocket arrangements, or some combination thereof.

Considering the recirculating ejector unit principle and referring to FIGURES 3 and 4, as high velocity air flows from the primary nozzles 19 and 23 of the units 20 and 24, this entrains secondary air streams from the atmosphere, causing a turbulent mixing of the primary and secondary air streams to occur in the mixing section of the units immediately downstream of the nozzles. Note mixing section 33 shown in the enlarged view, FIGURE 4. At the end of the mixing section, which generally may be regarded as the straight upper portion of the unit, mixing has occurred and as illustrated in FIGURE 4, the composite flow will in general be diffused up to the turning section 34 and then exhausted out the exit 35. This exhaust stream may hereinafter be referred to as the tertiary flow. The optimum jet angle at the exit 35 is such that at the design altitude of the craft and at design mass augmentation, there will be no adverse pressure gradient across the jet and the pressure interior to the circulating flow will be atmospheric. The existing jet then impinges on the ground in the manner of a uniform jet impinging on a fiat plate. From the laws of fluid continuity, the mass flow of the outer split stream must equal the mass flow introduced at the primary nozzle. This condition specifies the proper jet angle, which is typically approximately 25 degrees from the horizontal, although the angle under certain circumstances may be as low as zero degrees or as high as ninety degrees. The lift component due to jet reaction of course increases as the jet angle increases.

Referring to FIGURE 3, the ideal exhaust angle out) of recirculating ejector unit 24 is solely a function of the mass augmentation and can be expressed analytical- 1y as follows:

where m/m is the ratio of tertiary mass flow (m) to primary mass flow (m'), which ratio represents mass augmentation. Having defined the optimum exhaust angle, the amount of overhang 1, representing the dimension of recirculating ejector unit from inlet to the outer extemity of the exhaust duct as shown in FIGURE 3, can be determined with two additional variables; maximum design height, and inlet angle (0 As will be discussed later, the optimum combination of these angles and dimensions will be a function of factors such as performance, structural weight, and mission. The letter t in FIG. 3 refers to the thickness or dimension of the inlet of unit 24.

As revealed in FIGURE 4, the mixing section 33 is tplically of a length corresponding to five mixing section thicknesses, but in cases where parallel configurations of primary nozzles are used, the length can typically be shortened in direct ratio to the number of primary nozzles used therein. Appropriate boundary layer techniques employing sucking or blowing, as may be appropriate, may be used along the mixing section walls, diff-user and turning section. Sound absorbing and/ or flotation materials such as glass wool or foamed plastic may be used in space 36 between the center body 37 disposed in the recirculating ejector unit.

Over some regions of height it may be necessary or desirable to provide coanda-spoilers in the form of a flat plate located at the inner lip of the exit 35 or by undercutting the center body to prevent the exhausting air curtain from attaching to the base of the center body. Under some conditions of height, angles of intake and exhaust, and velocity of the recirculating air flow, it is possible to operate without the center body 37. As should now be apparent, the operating conditions surrounding the utilization of the recirculating ejector units according to our invention are of considerable importance. It should be noted that it is not sufficient to determine merely the inlet and exhaust angles which result in the highest base pressures, for when optimizing a configuration, other factors such as structural weight, overall size of vehicle and control effectiveness must be taken into consideration. In some instances it will be found that when optimizing with respect to height and mass flow, that the amount of overhang I, will be excessive, and this will occasion a compromise between these variables, depending upon the mission of the vehicle.

A major portion of the flow from exit 35 is recirculated as the secondary stream to the ejector, as indicated in FIGURE 4, and this forms a curved reverse flow angular jet that generates a base pressure greater than atmospheric in the same general manner as a conventional angular jet.

The following table is presented by way of illustration as to typical dimensions and other values associated with certain specified embodiments of our invention.

As to physical capabilities of the concept, the following table outlines the performance of four configurations:

Operating Size Gross Total Forward Height (ft) Weight ILP.

(ft.) (lbs) (m.p.h.)

Utility Barge As will be observed from FIGURE 6 the recirculating flow taking place in the recirculating ejector units is a 3-dimensional flow so to speak, and typically these recirculating ejector units extend entirely about the periphery of the machine.

As to the design of the recirculating ejector units, the high pressure nozzle arrangement is determined by several factors, including the primary pressure ratio and the dimension of the duct. As an example, the nozzles may be /2-inch in diameter and disposed upon 4-inch centers in instances in which a comparatively low pressure ratio is employed. A typical ratio of the area of the ejector unit inlet to the nozzle area is 200 to 600. The nozzles may be a multiplicity of discrete nozzles as shown in FIGURE 5 or alternatively may be in the form of a continuous slit, or discrete slits formed in the headers, the nozzles in each instance being located typically at or adjacent the mixing section inlet and disposed parallel to the centerline of the mixing section. The spacing between the nozzles is typically equal to the inlet thickness of the mixing section, with the nozzles usually being positioned or distributed in a symmetrical manner at the inlet of the mixing section. The inner contour of the primary nozzle 19 is such as to optimize the nozzle efliciency either as a subsonic or as a supersonic nozzle, for the desired pressure ratio and expansion ratio. These ratios are determined from the basic ejector performance equation, appearing hereinafter as Equation 4.

The large quantity of airflow from the exit of the re circulating ejector units extends substantially in a straight line that is directed downwardly and substantially inwardly so as to impinge upon the ground in the manner shown in FIGURE 4, the air then flowing substantially parallel to the ground and toward the center of the machine.

The equation for describing the performance of a recirculating ejector unit is obtained from the simultaneous solution of three equations, the first of these relating continuity, the second momentum, and the third being the energy equation.

where m is the. primary mass flow (slugs/sec), m" is the secondary mass flow (slugs/ sec.) and m is the tertiary mass flow (slugs/sec), and where mv is the momentum of the primary air, m"v is the momentum of the secondary air (lb.), mv is the momentum of the tertiary air (1b.) and F is normally the shear force (in lbs.) on the walls of the mixing sections; however, all internal flow losses can be accounted for in this term.

The v and v and v are the velocities in their respective flow terms. Equation 3 expresses mathematically that the total energy of the primary and secondary air flows must be equal to the total energy of tertiary air, and in this equation 7 is a gas constant, p is the density of air (slugs), p (lb/ft?) and p (lb/ft?) is the total pressure of their respective flow stream and p (lb/ft?) is the static pressure of the tertiary stream.

From these three basic equations we obtain the following expression which describes the performance of a recirculating ejector:

Having established the relationship of all the variables effecting the performance of a recirculating ejector, the performance of a GEM utilizing this concept may be determined.

The simplified approach utilizes the conventional thin jet momentum theory of annular jets as outlined in the David Taylor Model Basin Report identified as DTMB Aero Rpt. 923 by H. Chaplin. The base pressure determined in this manner gives a reason-ably close first estimate. In addition to the lift obtained from the base pressure over the base area, lift is obtained from the vertical component of the change in momentum of the flow in the duct of units 20 and 24, as well as in side units, if such be used; from the static pressure under the center body (in some cases negative); and a negative component from the primary jet reaction. A more sophisticated relationship involving a thick jet vortex theory with non-uniform velocity gradients and vehicle geometry can be used, but it does not appear that this added complexity is of moment for preliminary performance predictions.

Effective control of the craft must be provided throughout two distinct flight regimes defined by forward speed;

hovering and high speed forward flight. Inasmuch as two separate control systems are employed, there will obviously be an overlap during the transition period at low forward speeds where the hovering controls will become less effective and the high speed controls will become more effective. Generally speaking, the hovering controls will always consist of some method of redistributing, redirecting or throttling the recirculating air curtain. The high speed forward flight controls will consist of conventional aerodynamic surfaces as used on low speed aircraft. Considering first the controls for hovering:

Laterial and longitudinal control for our machine are furnished by a collective or differential throttling of the primary air piped to the recirculating thrust units, and directional control by collective deflection of forward vanes 42 and aft vanes 43, which are respectively disposed in the forward and rear recirculating thrust units.

Vanes 4-2 and 43 are preferably hinged at 41a and 41b, respectively, about their upper portions, and by simultaneous deflections, these vanes cause the existing air to be redirected, creating a yawing moment about a virtual vertical central axis of the machine. Vanes 43 operate in concert with vanes 42 so as to enhance the yawing moment, and as should be apparent, the rear vanes are deflected at all times in an opposite sense to the forward vanes so that the yaw tendency about the central vertical axis of the machine will be symmetrical. The vanes are typically operated by virtue of a mechanical linkage interconnected with the pilots steering mechanism, so that as the pilot moves, for example, his rudder pedals left or right, as the case may be, appropriate deflection of the vanes will be brought about.

Roll and pitch control of our machine is brought about by the selective use of designated sections of the recirculating ejector units. Preferably, the units are divided into two sections along the front and rear edges of the machine and two or more sections located along each side of the machine, with each of these sections being supplied from an individual header. From 20 to 40 nozzles are typically located on each header for the size machine illustrated.

Appropriate valving means is located in each supply duct to the headers so that the amount of air flowing to each header and from the nozzles of the header may be selectively controlled. This control includes control of the air to thrust unit 15. Referring to FIGURE 3, Valve 38 is located in forward duct 17, on the side of secondary header 18 nearest the plenum 16 and is remotely controlled from the cockpit compartment by the pilot. This valve could be according to any of the various types of construction and operation, but it must exhibit the properties of low pressure drop between inlet and outlet, adaptable to remote control such as by mechanical, electrical, pneumatic or hydraulic power, and have throttling characteristics which are reasonably linear. Similarly, valve 39 may be operably disposed in duct 21 and valve 40 in duct 25.

As a result of this construction, if it is desired to bank to the right, for example, in addition to deflecting the vanes by movements of the pedals, the pilot moves his control column to the right, this operating the valve or valves controlling the flow to the units on the left side of the machine, bringing about an increase in the flow of air to these units and causing the left side to rise somewhat with respect to the right side of the machine, thus to execute a properly banked turn to the right.

In a similar manner, pitch control is brought about by varying the flow of air to the front and rear headers, and for example if the steering column is pushed forward, the flow of air to the rear headers of the machine is increased whereas by pulling it towards the pilot, an increase of air to the front of the machine is brought about. A trim to compensate fora shift in the center of gravity of the machine is accomplished in the same manner, and low speed flight may be achieved by tilting the entire vehicle in the direction of travel.

Considering the control for high speed forward flight, forward propulsion control is obtained by selectively varying the flow of primary air to the thrust ejector 15. In addition, limited pitch and directional control can be obtained through the horizontal vanes 44 and vertical vanes 45 located in the backwash of the thrust unit 15. The large vertical stabilizer 46 will supply the required directional stability, and rudder 47 provides the necessary directional control; however, if additional pitching imoment trim is required, a horizontal stabilizer 48 shown in FIGURE 2 is used and the elevator 49 provides pitch control. These external aerodynamic surfaces operate in concert with the vanes located in the backwash of thrust unit 15.

In some embodiments of our invention, and as perhaps best seen in FIGURE 6, it may be necessary to incorporate schemes to increase the inherent static stability of the vehicle. This may be accomplished by partitioning the base or underside into two or more areas or compartments through the use of aerodynamic curtains or physical barriers. In this manner a different static pressure can be sustained in each compartment of the underside, and the cross-flow under the vehicle is minimized. It is the characteristic of peripheral air curtain ground effect machines that the pressure under the base increases progressively as the height of the base above the ground is decreased. Therefore, the compartment closest to the ground will necessarily contain the higher pressure and a moment tending to return the vehicle to a level attitude results without intervention from the pilot.

As also to be noted in FIGURE 6, the aerodynamic curtain may be created by the use of fore and aft cross slots 51 and 52 as well as right and left cross slots 53 and 54 for injecting high pressure fluid downwardly at high velocity. The jets constituting the means for creating the aerodynamic curtain are of considerably smaller dimension than that associated with recirculating ejector units, and the total jet cross sectional area associated with the use of the stabilizing slots is typically of the total area of the outlet portions of the recirculating ejector units. The source of the air for the jet curtains will typically be the same as the source of primary air for the recirculating ejector units.

Shown in FIGURE 6 are inlet and exhaust slots of the recirculating ejector units, which run the full width of the base at the front and rear of the vehicle. For a full peripheral curtain configuration of rectangular plan form, it is not necessary to extend the inlet slot beyond the intersection with an adjacent inlet slot. In other words, when the plan form contains sides which intersect, it is sufficient to provide a continuous inlet, and the exhaust ducting may be segmented with the corners left out.

As to the use of arresting gear on this type vehicle, it should be borne in mind that some configurations will exhibit a lift capability with height such that below a critical height the vehicle will be drawn toward the ground surface. This height is typically one to two times the thickness of the exhaust nozzle 35.

As will be apparent to those skilled in this art, our machine can take other forms than that of the essentially rectangular configuration depicted herein. For example, the machine could be circular, oblong, or even triangular in some instances.

As to the recirculating ejector units, although we prefer a flow direction as illustrated in FIGURE 3, if desired we can reverse the flow by placing the ejector nozzles in outer portion of the recirculating ducts if such an arrangement for any reason appears advantageous. However, as will be understood, some degree of redesign of the ejector units will be necessary. In this arrangement, as in the principal embodiment, it may be possible in some instances to eliminate entirely the use of the center body.

Although we have principally mentioned the use of a prime mover aboard our machine for supplying compressed gas, it is within the contemplation of our invention to use other sources, such as steam from a self-contained steam generator, or products from a chemical or thermal reaction for supply of high pressure primary fluid. Even a so-called blow-down system could be used for small, low expense applications, in which pressurized gas from a bottle source could be used.

As will be understood, the spirit of our invention can be employed in a range of embodiments far Wider than that set forth herein, and we are not to be limited except as required by the scope of the appended claims.

We claim:

1. A ground effect machine utilizing recirculation techniques for creating and sustaining a pressure on the underside of said machine for a major portion of its support comprising a plurality of recirculating ejector units disposed on at least a portion of the periphery of the machine, each of said units comprising a curved duct having substantial dimension along the periphery of said machine, and having adjacent inlet and outlet slots disposed along the underside of the peripheral edge of said machine, injection means for injecting quantities of high velocity primary compressed fluid into said inlet slots in a direction such that said primary fluid will tend to flow through said curved ducts and thereafter emanate from said outlet slots, said primary fluid causing a substantial portion of the fluid emanating from said outlet slots to be drawn into said inlet slots, thereby to establish a recirculating flow through said ducts, said recirculating flow serving to create and sustain a pressure on the underside of said machine greater than ambient pressure whereby said machine is lifted as a result of the change of momentum of said recirculating flow as well as due to the sustaining of pressure on the underside of said machine, said machine having front, back and side portions, at least one of said recirculating ejector units disposed on each of said front, back and side portions, each of said units having control means for controlling the amount of primary compressed fluid flowing to said injection means whereby by changing the lift contributed by each unit, the height of the machine above the operating surface as well as the individual height of any one portion of the machine can be controlled.

2. A ground effect machine supported and propelled entirely by the use of compressed gas, comprising a plurality of recirculating ejector units disposed on at least a portion of the periphery of said machine, and a thrust unit for propelling the machine over the operating surface, said thrust unit having an inlet slot for the admission of atmospheric air, each of said recirculating ejector units having adjacent inlet and outlet slots, with a curved duct interconnecting said slots, a source of compressed gas in said machine, a plurality of nozzles directed into the inlet slots of each of said recirculating ejector and thrust units, duct means for directing a flow of compressed gas into said inlet nozzles of said thrust unit so as to cause a substantial mass of atmospheric air :to be educted for the propulsion of said machine, other duct means for directing a flow of compressed gas into said inlet nozzles of said recirculating ejector units so as to cause a substantial flow through the curved ducts thereof, the outlet slots of latter units discharging a flow of gas and air adjacent said inlet slots, a substantial portion of the latter flow being drawn into said inlet slots, thus to establish a recirculating flow, which serves to create a substantial pressure on the underside of said machine for supporting same by ground effect principle, control means for selectively proportioning the flow of compressed gas to the nozzles of said recirculating ejector units for control purposes, and vanes in the outlet portions of said recirculating ejector units for controlling the direction of flow therefrom.

3. The ground etfect machine as. defined in claim 2 in which said compressed gas generating means is a jet engine, the exhaust of which is conducted to a portion of said thrust unit to enhance the characteristics of the flow therethrough.

4. A ground effect machine utilizing a plurality of recirculating ejector units disposed aiong at least a portion of its periphery, each of said units having adjacent inlets and outlets interconnected by curved duct means having substantial dimension in the direct-ion along the periphery of said machine, gas injection means in the inlet of each of said units for injecting high pressure gas, thus to cause a substantial amount of secondary flow to enter said inlet, including the flow of gas from said outlet, thus to establish a recirculating flow serving to create and sustain a pressure on the underside of said machine for the support of same, each of said outlets being angled so as to cause the flow of air to the underside of said machine, means tor selectively modulating the flow of compressed gas to said gas injection means, means for selectively controlling the direction of flow from each of said outlets, thereby enabling said machine to have satisfactory control characteristics, and a plurality of fluid carrying ducts provided in essentially intersecting relationship on the underside of said machine, each of latter ducts having slots therein which serve to subdivide the underside of said machine by injecting a curtain of high pressure gas downwardly at high velocity, the thus compartmented underside of said machine serving as a self-correcting trim for said machine.

5. A ground effect machine employing recirculation techniques and utilizing means for proportioning the amount of air directed to the various portions of the perimeter of said machine in order to achieve efiective flight control, said machine having a plurality of recirculating ejector units disposed about a substantial portion of the periphery of said machine, each of said recirculating ejector units being substantially curved in crosssection and having adjacent inlet and outlet slots disposed along the underside of the peripheral edge of said machine, means in the inlet slots of each of said units arranged to inject a flow of compressed gas into said inlet slots to cause a substantial mass of air to be educted and flow through said units and thereafter emanate from said outlet slots, said outlet slots discharging flow adjacent said inlet slots, thereby causing a substantial portion of said flow to be drawn into said inlet slots and thus to establish a recirculating flow which serves to create a substantial pressure on the underside of said machine for supporting same by ground effect principle, and means for selectively proportioning the flow of compressed gas to said injection means of said units for control purposes, said mean-s for proportioning including means for proportioning the flow between the front and back units of the machines as well as between the sides of the machine, whereby a turn can be facilitated by causing the machine to bank in the proper direction.

6. The machine as defined in claim 5 in which yawcontrolling vanes are disposed in the outlet slots of the fore and aft units for selectively controlling the direction in which flow emanates from said outlet slots, said vanes being differentially operable so as to tend to cause said machine to turn about a center point.

References Cited by the Examiner UNITED STATES PATENTS 2,736,514 2/1956 Ross -7 2,876,965 3/1959 Streib 180-7 2,969,751 1/1961 Toulmin 180-7 3,045,947 7/ 1962 Bertin et al. 244-52 FOREIGN PATENTS 219,133 11/1958- Australia. 1,240,721: 8/ 1960 France. 1,263,704 5/1961 France.

137,405 4/1961 U.S.S.R.

OTHER REFERENCES David Taylor Model Basin (DTMB) Aero Report 994; December 1960.

A. HARRY LEVY, Primary Examiner. 

1. A GROUND EFFECT MACHINE UTILIZING RECIRCULATION TECHNIQUES FOR CREATING AND SUSTAINING A PRESSURE ON THE UNDERSIDE OF SAID MACHINE FOR A MAJOR PORTION OF ITS SUPPORT COMPRISING A PLURALITY OF RECIRCULATING EJECTOR UNITS DISPOSED ON AT LEAST A PORTION OF THE PERIPHERY OF THE MACHINE, EACH OF SAID UNITS COMPRISING A CURVED DUCT HAVING SUBSTANTIAL DIMENSION ALONG THE PERIPHERY OF SAID MACHINE, AND HAVING ADJACENT INLET AND OUTLET SLOTS DISPOSED ALONG THE UNDERSIDE OF THE PERIPHERAL EDGE OF SAID MACHINE, INJECTION MEANS FOR INJECTING QUANTITIES OF HIGH VELOCITY PRIMARY COMPRESSED FLUID INTO SAID INLET SLOTS IN A DIRECTION SUCH THAT SAID PRIMARY FLUID WILL TEND TO FLOW THROUGH SAID CURVED DUCTS AND THEREAFTER EMANATE FROM SAID OUTLET SLOTS, SAID PRIMARY FLUID CAUSING A SUBSTANTIAL PORTION OF THE FLUID EMANATING FROM SAID OUTLET SLOTS TO BE DRAWN INTO SAID INLET SLOTS, THEREBY TO ESTABLISH A RECIRCULATING FLOW THROUGH SAID DUCTS, SAID RECIRCULATING FLOW SERVING TO CREATE AND SUSTAIN A PRESSURE ON THE UNDERSIDE OF SAID MACHING GREATER THAN AMBIENT PRESSURE WHEREBY SAID MACHINE IS LIFTED AS A RESULT OF THE CHANGE OF MOMENTUM OF SAID RECIRCULATING FLOW AS WELL AS DUE TO THE SUSTAINING OF PRESSURE ON THE UNDERSIDE OF SAID MACHINE, SAID MACHINE HAVING FRONT, BACK AND SIDE PORTIONS, AT LEAST ONE OF SAID RECIRCULATING EJECTOR UNITS DISPOSED ON EACH OF SAID FRONT, BACK AND SIDE PORTIONS, EACH OF SAID UNITS HAVING CONTROL MEANS FOR CONTROLLING THE AMOUNT OF PRIMARY COMPRESSED FLUID FLOWING TO SAID INJECTION MEANS WHEREBY BY CHANGING THE LIFT CONTRIBUTED BY EACH UNIT, THE HEIGHT OF THE MACHINE ABOVE THE OPERATING SURFACE AS WELL AS THE INDIVIDUAL HEIGHT OF ANY ONE PORTION OF THE MACHINE CAN BE CONTROLLED. 